People living with HIV are strongly advised to adhere to antiretroviral therapy (ART) in order to decrease HIV-related morbidities, increase longevity, and decrease infectiousness. They are also strongly advised to avoid risky sex behaviors to avoid HIV super-infection and other sexually transmitted infections, and to reduce the likelihood of transmitting HIV to an uninfected partner. However, life stress and its consequences (e.g., depression) make it challenging for these individuals to follow these medical recommendations. Preliminary research suggests that mindfulness training (MT) can help people living with HIV cope more effectively with stress. Although encouraging, this research has methodological limitations, and there is limited or no information regarding the possible effect of MT on ART adherence and sexual risk reduction. Further, MT has typically been delivered in formats (i.e., weekly group sessions, weekend workshops) that are infeasible for people living with HIV, who are disproportionately low-income and often lack the resources needed to participate in traditional MT. The goals of this R34 exploratory clinical trial are to determine the feasibility ad acceptability of phone-delivered MT, and to obtain preliminary evidence of its efficacy for ART adherence and sexual risk reduction. Completion of this research is necessary prior to conducting a R01-supported, Phase III randomized clinical trial to formally test the efficacy of MT for ART adherence and sexual risk reduction. Consistent with PAR-14-182, we propose a formative and a pilot phase. The formative phase will involve adapting our existing telephone-based MT intervention to the HIV context (Aim 1), developing a time- and attention-matched comparison condition (Aim 2), and refining our assessment protocol (Aim 3). During the formative phase, we will finalize the study protocols and consents, develop a manual of operations, and obtain regulatory approvals. Next, during the pilot phase, we will implement both interventions and the evaluation protocol to determine their feasibility and acceptability (Aim 4). HIV+ outpatients (N = 50) will be recruited, assessed at baseline, randomly assigned to MT (n = 25) or to a control intervention (n = 25), and re-assessed at post-intervention and at a 3-month follow-up. Feasibility and acceptability will be assessed using mixed methods. We will also obtain preliminary estimates of effect sizes for ART adherence and risky sex behavior as well as for the hypothesized mediators of mindfulness training (i.e., depression, perceived stress, impulsivity). We propose several innovations to improve upon prior research. First, we will use a novel and scalable method to deliver MT. Second, we will explore the usefulness of MT for ART adherence and sexual risk reduction, targets rarely addressed in prior MT research. Third, we will target modifiable determinants of non- adherence (e.g., depressive symptoms) and risky sex (e.g., impulsivity). Fourth, we will address limitations of the extant research by sampling at-risk persons; employing a time- and attention-matched comparison condition; and using self-reported, objective, and biological measures of ART adherence and risky sex.